Xenon Pharmaceuticals Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 14A

Proxy Statement Pursuant to Section 14(a) of the Securities

Exchange Act of 1934 (Amendment No. )

Filed by the Registrant☒

Filed by a Party other than the Registrant☐

Check the appropriate box:

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

Payment of Filing Fee (Check all boxes that apply):

NOTICE OF ANNUAL MEETING OF SHAREHOLDERS

NOTICE IS HEREBY GIVEN that the annual meeting (the “Meeting”) of the shareholders of Xenon Pharmaceuticals Inc. (“Xenon” or the “Corporation”) will be held virtually via live webcast on Tuesday, June 2, 2026 at 9:30 a.m. (PDT) at https://www.proxydocs.com/XENE for the following purposes:

to receive the financial statements of the Corporation for the financial year ended December 31, 2025 and the report of the Corporation’s auditor thereon;

to elect as directors of the Corporation the eight nominees named in the accompanying Proxy Statement and Management Information Circular to hold office until the next annual meeting of the Corporation or until their successors are duly elected;

to approve, on an advisory basis, the compensation of the Corporation’s named executive officers;

to approve, on an advisory basis, the frequency of future shareholder advisory votes to approve the compensation of the Corporation’s named executive officers;

to approve the Corporation’s 2026 Equity Incentive Plan (the “2026 Plan”);

to appoint PricewaterhouseCoopers LLP (“PwC”) as the Corporation’s auditor to hold office until the next annual meeting of the Corporation;

to authorize the Audit Committee of the board of directors of the Corporation to fix the remuneration to be paid to the auditors of the Corporation; and

to conduct such other business as may properly be brought before the Meeting or any adjournment thereof.

The accompanying Proxy Statement and Management Information Circular provides additional information as to the matters to be dealt with at the Meeting and is deemed to form a part of this Notice. The holders of common shares of the Corporation (the “Common Shares”) of record at the close of business on April 7, 2026 (the “Record Date”) are entitled to receive notice of and to vote at the Meeting.

The Corporation is availing itself of the “notice-and-access” provisions in securities laws that permit the Corporation to forgo mailing paper copies of the Proxy Statement and Management Information Circular and other proxy-related materials (the “Meeting Materials”) to shareholders of the Corporation and instead make them available for review, print and download via the internet. The Meeting Materials can be accessed on the Corporation’s website at https://investor.xenon-pharma.com, under the Corporation’s SEDAR+ profile atwww.sedarplus.ca and on EDGAR atwww.sec.gov. Shareholders may also request to receive printed copies of the Meeting Materials, at no extra cost, over the internet at https://www.investorelections.com/XENE, by telephone at 1-866-648-8133, or by email at paper@investorelections.com. In order to receive a paper package in time for the Meeting, you must make this request on or before May 21, 2026. Before voting, shareholders are reminded to review the Proxy Statement and Management Information Circular.

Xenon will hold the Meeting in a virtual-only format, which will be conducted online via live webcast. Only shareholders of record, as of the Record Date, and duly appointed proxyholders may attend and participate in the Meeting, including voting and asking questions during the Meeting. Non-registered shareholders (being those who beneficially own Common Shares that are registered in the name of an intermediary) who have not duly appointed themselves as proxyholder will be able to attend the Meeting online as guests, but will not be able to vote or ask questions at the Meeting. To attend the Meeting, you must register at https://www.proxydocs.com/XENE. Upon completing your registration, you will receive further instructions via email, including a unique link that will allow you access to the Meeting and to vote and submit questions during the Meeting.

As part of the registration process, you must enter the control number located on your proxy card, voting instruction form, or Notice of Internet Availability. If you are a beneficial owner of shares registered in the name of a broker, bank, or other nominee, you will also need to provide the registered name on your account and the name of your broker, bank, or other nominee as part of the registration process.

A shareholder that wishes to appoint a person other than the management nominees identified on the form(s) of proxy or voting instruction form, as applicable, to represent him, her or it at the Meeting may do so by inserting such person’s name in the blank space provided in the form(s) of proxy or voting instruction form, as applicable, and following the instructions for submitting such form of proxy or voting instruction form, as applicable. This must be completed prior to registering such proxyholder, which is an additional step to be completed once you have submitted your applicable form(s) of proxy or voting instruction form. If you wish that a person other than the management nominees identified on the applicable form(s) of proxy or voting instruction form attend and participate at the Meeting as your proxy and vote your Common Shares, including if you are a non-registered shareholder and wish to appoint yourself as proxyholder to attend, participate and vote at the Meeting, you MUST register such proxyholder after having submitted your applicable form(s) of proxy or voting instruction form, as applicable, identifying such proxyholder. Failure to register the proxyholder will result in the proxyholder not receiving a control number to participate at the Meeting (a “Control Number”). Without a Control Number, proxyholders will not be able to participate or vote at the Meeting. To register a proxyholder, shareholders MUST provide their proxyholder’s contact information to Mediant/BetaNXT by email to DSMsupport@BetaNXT.com, so that Mediant/BetaNXT may provide the proxyholder with a Control Number via email.

Proxies for Common Shares to be used at the Meeting must be received by Mediant/BetaNXT not later than 11:59 p.m. (PDT) on Monday, June 1, 2026 (or, if the Meeting is adjourned, not later than 48 hours, excluding Saturdays, Sundays and holidays, preceding the time of such adjourned Meeting). Proxies may be submitted by one of the following alternative methods:

By Internet: If you received the Notice or a printed copy of the Proxy Materials, follow the instructions in the Notice or on the proxy card.

By Telephone: If you received a printed copy of the Proxy Materials, follow the instructions on the proxy card.

By Mail: If you received a printed copy of the Proxy Materials, complete, sign, date, and mail your proxy card in the enclosed, postage-prepaid envelope.

DATED at Vancouver, British Columbia this 22nd day of April, 2026.

By order of the board of directors

/s/ Ian Mortimer

Ian Mortimer

President and Chief Executive Officer

Table of Contents

PROXY STATEMENT AND

MANAGEMENT INFORMATION CIRCULAR

Annual Meeting of Shareholders

to be held on Tuesday, June 2, 2026